 /*******************************************************************************
  * Copyright (c) 2000, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/

 package org.eclipse.ui.activities;

 import java.util.Set ;

 /**
  * An instance of this interface is a category as defined by the extension
  * point <code>org.eclipse.ui.activities</code>.
  * <p>
  * An instance of this interface can be obtained from an instance of
  * <code>IActivityManager</code> for any identifier, whether or not a category
  * with that identifier is defined in the extension registry.
  * </p>
  * <p>
  * The handle-based nature of this API allows it to work well with runtime
  * plugin activation and deactivation, which can cause dynamic changes to the
  * extension registry.
  * </p>
  * <p>
  * This interface is not intended to be extended or implemented by clients.
  * </p>
  *
  * @since 3.0
  * @see IActivityManager
  */
 public interface ICategory extends Comparable {

     /**
      * Registers an instance of <code>ICategoryListener</code> to listen for
      * changes to properties of this instance.
      *
      * @param categoryListener
      * the instance to register. Must not be <code>null</code>.
      * If an attempt is made to register an instance which is
      * already registered with this instance, no operation is
      * performed.
      */
     void addCategoryListener(ICategoryListener categoryListener);

     /**
      * Returns the set of category activity bindings for this instance.
      * <p>
      * This method will return all category activity bindings for this
      * instance, whether or not this instance is defined.
      * </p>
      * <p>
      * Notification is sent to all registered listeners if this property
      * changes.
      * </p>
      *
      * @return the set of category activity bindings. This set may be empty,
      * but is guaranteed not to be <code>null</code>. If this set is
      * not empty, it is guaranteed to only contain instances of <code>ICategoryActivityBinding</code>.
      * @see ICategoryActivityBinding
      */
     Set getCategoryActivityBindings();

     /**
      * Returns the identifier of this instance.
      *
      * @return the identifier of this instance. Guaranteed not to be <code>null</code>.
      */
     String getId();

     /**
      * Returns the name of this instance suitable for display to the user.
      * <p>
      * Notification is sent to all registered listeners if this property
      * changes.
      * </p>
      *
      * @return the name of this instance. Guaranteed not to be <code>null</code>.
      * @throws NotDefinedException
      * if this instance is not defined.
      */
     String getName() throws NotDefinedException;

     /**
      * Returns the description of this instance suitable for display to the user.
      * <p>
      * Notification is sent to all registered listeners if this property
      * changes.
      * </p>
      *
      * @return the description of this instance. Guaranteed not to be <code>null</code>.
      * @throws NotDefinedException
      * if this instance is not defined.
      */
     String getDescription() throws NotDefinedException;

     /**
      * Returns whether or not this instance is defined.
      * <p>
      * Notification is sent to all registered listeners if this property
      * changes.
      * </p>
      *
      * @return <code>true</code>, iff this instance is defined.
      */
     boolean isDefined();

     /**
      * Removes an instance of <code>ICategoryListener</code> listening
      * for changes to properties of this instance.
      *
      * @param categoryListener
      * the instance to remove. Must not be <code>null</code>.
      * If an attempt is made to remove an instance which is not
      * already registered with this instance, no operation is
      * performed.
      */
     void removeCategoryListener(ICategoryListener categoryListener);
 }

